The post-convention advantage goes to the Democrats

The polls will bounce up and down over the next few weeks, but as the last balloons were popping in Philadelphia, it was clear that the Democratic convention won the battle of lasting impressions.

During its early hours, the event was shaping up as an image nightmare. Supporters of Bernie Sanders booed and jeered, leading Sarah Silverman to say, "To the Bernie or bust people, you're being ridiculous." It's a problem when the most serious person in the hall is the comedian. Donald Trump gleefully tweeted that it was "a total meltdown." His own poll numbers had risen following the GOP convention in the week before, and he was undoubtedly hoping that Philadelphia would drag down Clinton's.

Those hopes vanished when Michelle Obama took the podium. She was eloquent and effective, and she delivered a particularly memorable line: "I wake up every morning in a house that was built by slaves." On the first night of the GOP convention, Melania Trump also had memorable lines. Unfortunately, she plagiarized them from Mrs. Obama.

On Tuesday night, jaded journalists rolled their eyes as Bill Clinton spoke of his life with Hillary Clinton. Their first meeting in the law library, her work as first lady of Arkansas, her health care advocacy in the 1990s – all of it was familiar to the senior press corps. But they overlooked something very important: It has been more than 15 years since he left office, so most voters under the age of 35 or so had never heard those stories before. To these younger voters – many of whom supported Sanders in the primaries – the intimate biography was a revelation. No doubt the Clinton camp hoped that they would see her in a new and more flattering light.

On the third day, Trump tried to seize media attention with a bizarre press conference in which he appeared to invite the Russians to hack Hillary Clinton's emails. The comment led to immediate speculation about Trump's businesses connections to Russia – a mashup of "The Americans" and "House of Cards." The remark even led some to wonder aloud whether Trump had actually committed treason. As Yogi Berra might have put it: If Joe McCarthy were alive, he would be spinning in his grave.

Just as significant, he also suggested that he would recognize the Russian annexation of Crimea, an act of aggression as naked as anything that the world has seen since the 1930s. One suspects that he has given his critics a new good news/bad news joke. The good news is that Trump is not Hitler. The bad news is that he is Neville Chamberlain.

Like Mike Pence on the third night of the GOP convention, Tim Kaine came across as a decent man committed to his party's ideals. Both Pence and Kaine are decent men who gave solid, if not game-changing speeches. If social media is any guide, many people are wondering whether the country would be better off if the veep candidates were at the top of their tickets.

The speeches by Vice President Biden, President Obama and Hillary Clinton herself emphasized the classic themes of faith, family and patriotism. In recent years, Republicans have often given more rhetoric emphasis to these ideas, but by nominating Trump, they tossed away their traditions. When the Clintons spoke about their experiences as parents, they subtly reminded people of Trump's 2005 words: "I'll supply funds and she'll take care of the kids." His slogan, "Make America Great Again" invites the comeback – which we heard repeatedly in Philadelphia – that America is already great. Democrats also pounced on his assertion that "I alone can fix it." Hillary Clinton responded: "Really? I alone can fix it? Isn't he forgetting troops on the front lines, police officers and fire fighters who run toward danger. ... He's forgetting every last one of us."